wonder bolt

trying to make my own wonder bolt any1 know the length and size of this bolt?

Long&Short,

 

 I will try to do too, the length is 1 1/4" the size...

Long&Short,

 

 I will try to do too, the length is 1 1/4" the size...

The correct size for fins box is 3/16" x 3/4"